A video and/or audio disc has recorded thereon not only video and/or audio information but also address signals respectively allocated to pieces of video and/or audio information. Desired pieces of video and/or audio information can thus be reproduced by picking up the address signal allocated to the particular pieces of information.
A video and/or audio disc information recording and reproducing apparatus, to play back such a disc, includes pickup means to pick up the information recorded on the disc rotating on a turntable, coarse tracking control means operative to coarsely vary the respective positions of the turntable and the pickup means relative to each other in a radial direction of the disc on the turntable, and fine tracking control means operative to minutely vary the relative positions of the turntable and the pickup means. In the case of an optical video and/or audio disc information recording and reproducing apparatus, the fine tracking control means comprises a tracking mirror which utilizes a beam of, for example, a laser, directed at a target information track of the disc. The tracking mirror is driven to deviate the laser beam in a radial direction of the disc so that the laser beam reflected from the mirror is correctly incident on the target track of the disc. The coarse tracking control means comprises a carriage carrying either the turntable or the pickup means and movable with respect to the pickup means or the turntable, respectively.
In a recording and reproducing apparatus of this nature, a desired address signal is picked up by comparing the latest address reached by the signal pickup beam with the address to be searched and driving the carriage for movement at a relatively high speed regulated on the basis of the detected difference between the address picked up and the address being searched. Difficulties are however encountered in searching an address in this manner since the carriage is liable to overrun or underrun the correct position in order to access the desired address when the detected difference between the latest address reached by the pickup beam and the address is utilized in the search. Such difficulties result from the force of inertia produced in the carriage being moved and the eccentricity which the disc inevitably has. To overcome these difficulties, the coarse tracking control is disabled before the desired address is reached by the signal pickup beam. After the the coarse tracking control means is thus made inoperative, the fine tracking control means is put into operation until the desired address signal is picked up by the pickup beam. The search for the address by the fine tracking control means is effected at a speed equal to the tracking speed for reproduction and, for this reason, can not be completed in a short period of time. The present invention contemplates provision of a method of searching for a desired address from a disc correctly and at a high speed.